1. Field of the Invention
The present invention generally relates to a noise reduction circuit and method. More specifically, the present invention relates to a noise reduction circuit and method that can be applied to a video display apparatus or a video recording/reproducing apparatus, for example.
2. Background Information
A conventional method to reduce noise in video data is disclosed in JP 2002-223374A. JP 2002-223374A discloses a noise reduction method, in which pixels of the same position in an image in a plurality of frames of an input video signal are extracted, noise is determined based on a signal change of the pixels between the frames, and a reduction procedure is performed. However, when using only a noise reduction process that is based only on the signal change between frames, as in the above-described conventional method, the time difference at which the signal change is obtained is large. Further, it is not possible to reduce noise effectively without using a complex circuit for moving parts.
Moreover, in the above-described conventional method, another problem was that the effect of the noise reduction for static parts is large and memory capacity is enlarged because it requires a plurality of memories of the size of one frame or a memory with the capacity of at least two frames.
Furthermore, yet another problem in the above-described conventional method was that a time difference between an audio signal and a video signal is generated because a delay of at least one frame arises in the noise reduction process and additional and considerable memory capacity and complex circuits are needed in correcting the delay.
Therefore, a noise reduction circuit and method that effectively reduce the noise with a simple structure regardless of the partial content of the image while suppressing process delay as well the capacity of the image memory used are desired.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved a noise reduction circuit and method. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.